The present invention is directed to medical articles, such as wound dressings. Such articles are useful in the treatment of skin lesions, for example.
Wound dressings should preferably absorb exudate from lesions without adhering to wound surfaces or floating away from the wound surface. Adhesion problems can occur when the wound has dried out due to the lack of production of exudate. Attempts to remove the dressing will result in disturbance of the newly forming layer of the skin over the wound and hence wound healing is delayed. The problem of dressings that float away from exuding lesions typically occurs when the wound produces particularly large volumes of exudate. Solutions to such problems involve, for example, using a continuous layer that retards the rate of loss of water, thereby preventing adhesion of the dressing to the wound, or providing the dressing with holes so that the exudate can pass through the holes to an absorbent, thereby keeping the dressing in contact with the wound.
It is desirable for effective wound healing to have wound dressings that do not allow the wound to dry out completely and that do not allow exudate to pool. Thus, a breathable wound dressing is desired that can absorb exudate, but not allow the wound to dry out. There are known wound dressings that include foams that attempt to address these problems; however, these dressings can have problems with breathability and swelling of the foam, which can place pressure on the wound, or alternatively, with poor absorption of exudate.
Thus, many of the known wound dressings are not free of disadvantages since what may be an excellent dressing for one kind of wound will be unsuitable for many other wounds because of the differences in the output of exudate. Thus, additional wound dressings are still needed that are suitable for use on a number of different wound types.
The present invention provides medical articles, such as wound dressings. In one embodiment, the medical article includes a backing, an absorbent foam, and a fibrous adhesive disposed between the backing and the absorbent foam, wherein the backing includes a liquid-impervious, moisture-vapor permeable polymeric film. In another embodiment, the medical article includes a backing, an absorbent, substantially nonswellable foam, and an adhesive disposed therebetween. In yet another embodiment, the medical article includes a backing, a foam, and a fibrous adhesive disposed therebetween.
Preferably, the medical articles have a dry MVTR of less than about 2000 g/m2/24 hours and a wet MVTR of at least about 3000 g/m2/24 hours at 38xc2x0 C. and 20% relative humidity. Preferably, the medical articles have a wet MVTR of at least about 5000 g/m2/24 hours at 38xc2x0 C. and 20% relative humidity.
Preferably, the liquid-impervious, moisture-vapor permeable polymeric film has a dry MVTR of at least about 300 g/m2/24 hours at 38xc2x0 C. and 20% relative humidity. Preferably, it has a wet MVTR of at least about 3000 g/m2/24 hours at 38xc2x0 C. and 20% relative humidity. For certain embodiments, the liquid-impervious, moisture-vapor permeable polymeric film comprises one or more layers. Preferably, the liquid-impervious, moisture-vapor permeable polymeric film is a thermoplastic polyurethane.
The foam is preferably absorbent and absorbs greater than 250 wt-% aqueous saline solution when immersed in phosphate buffered saline containing 0.9 wt-% NaCl at 37xc2x0 C. for 30 minutes. Preferably, the foam is also substantially nonswellable and increases in volume by no greater than about 10% following a 30-minute soaking in phosphate buffered saline at 37xc2x0 C. For certain preferred embodiments the foam is an open cell foam. Preferably, the foam is a polyurethane foam.
For certain embodiments, the backing includes a liquid-impervious, moisture-vapor permeable polymeric film and a nonwoven web. The liquid-impervious, moisture-vapor permeable polymeric film can be disposed between the nonwoven web and the foam, or the nonwoven web can be disposed between the liquid-impervious, moisture-vapor permeable polymeric film and the foam. The moisture-vapor polymeric film can be bonded to the nonwoven web with a fibrous adhesive, such as a polyacrylate fibrous adhesive, or thermomechanically, for example.